Jake M. Najman

Chronicity, Severity, and Timing of Maternal Depressive Symptoms: Relationships with Child Outcomes at Age 5.

The relationships between severity, chronicity, and timing of maternal depressive symptoms and child outcomes were examined in a cohort of 4,953 children. Mothers provided self-reports of depressive symptoms during pregnancy, immediately postpartum, and when the child was 6 months old and 5 years old. At the age 5 follow-up, mothers reported on childrens behavior and children completed a receptive vocabulary test. Results suggest that both the severity and the chronicity of maternal depressive symptoms are related to more behavior problems and lower vocabulary scores in children. The interaction of severity and chronicity of maternal depressive symptoms was significantly related to higher levels of child behavior problems. Timing of maternal symptoms was not significantly related to child vocabulary scores, but more recent reports of maternal depressive symptoms were associated with higher rates of child behavior problems.

Associations of Gestational Weight Gain With Offspring Body Mass Index and Blood Pressure at 21 Years of Age Evidence From a Birth Cohort Study

Background— Maternal weight gain in pregnancy is positively associated with offspring body mass index (BMI) and obesity risk in childhood, but whether this increased risk extends into adulthood or results in increases in other cardiovascular risk factors such as elevated blood pressure (BP) is unclear. Methods and Results— We used a population-based birth cohort of 2432 individuals (50% male) born in Brisbane, Australia, between 1981 and 1983 to prospectively examine the association between maternal gestational weight gain (GWG) and offspring BMI and BP at 21 years. On average, each mother gained 14.8 kg (SD, 5.1 kg) during her pregnancy. At 21 years of age, offspring mean BMI, systolic BP, and diastolic BP were 24.2 kg/m2 (SD, 4.9 kg/m2), 116.4 mm Hg (SD, 14.5 mm Hg), and 67.7 mm Hg (SD, 8.5 mm Hg), respectively. Offspring BMI was on average 0.3 kg/m2 (95% confidence interval, 0.1 to 0.4 kg/m2) higher for each 0.1-kg/wk greater GWG after adjustment for potential confounding factors. Systolic BP also was greater (0.2 mm Hg per 0.1 kg; 95% confidence interval, −0.2 to 0.6) in offspring whose mothers had higher GWG. Although this association was not statistically significant, it was consistent in magnitude with the association of maternal GWG with offspring BMI and of offspring BMI with BP. Conclusions— Our findings show that greater GWG is associated with greater offspring BMI into early adulthood and that this may translate into higher systolic BP in offspring. Further large studies are required to confirm an effect of GWG on a range of offspring cardiovascular risk factors.

Cohort Profile Update: The Mater-University of Queensland Study of Pregnancy (MUSP)

The Mater-University of Queensland Study of Pregnancy (MUSP) and its outcomes began in 1981 with data collected on 7223 pregnant woman-child pairs (6753 mothers, of whom 520 had 2 study children, less 50 who had multiple births). These women, and their children, were initially followed for up to 21 years. Since then there have been additional follow-ups of the mothers (27 years) and their children (30 years). There has also been a substantial increase in the breadth of topics addressed, with the collection of biological samples, the administration of structured clinical assessments of mental health and cognitive capacity, and markers of physical health such as lung function and blood pressure. MUSP was originally developed as a birth cohort study. It has become a longitudinal study of growth, development and ageing with an emphasis on the generational transmission of a wide range of factors impacting on adult health outcomes. We welcome interest in our study; for study background and publications visit [www.socialscience.uq.edu.au/musp] or contact [j.najman@uq.edu.au].

Associations of Parental, Birth, and Early Life Characteristics With Systolic Blood Pressure at 5 Years of Age Findings From the Mater-University Study of Pregnancy and Its Outcomes

Background—We examined the associations of a range of parental and early life characteristics with systolic blood pressure at 5 years of age. Methods and Results—Information from 3864 children who were followed up prospectively from their mother’s first antenatal clinic assessment was used. Maternal age, body mass index, and smoking during pregnancy were all positively associated with offspring systolic blood pressure at 5 years of age. The systolic blood pressure of children whose mothers had smoked throughout pregnancy was on average 0.92 mm Hg (95% CI 0.17 to 1.68) greater than that of children whose mothers had never smoked, after full adjustment. Children who had been breast fed until at least 6 months had lower systolic blood pressure than those who were breast fed for a shorter duration. Paternal body mass index and child’s weight, height, and body mass index were all positively associated with blood pressure at age 5. Conclusions—Because childhood blood pressure tracks into adulthood, interventions aimed at early life risk factors, such as quitting smoking during pregnancy, breast feeding, and prevention of obesity in all family members, may be important for reducing the population distribution of blood pressure and thus cardiovascular disease risk.

Associations of excess weight gain during pregnancy with long-term maternal overweight and obesity: evidence from 21 y postpartum follow-up

BACKGROUND The contribution of gestational weight gain (GWG) to the development of obesity may have important implications for mothers in their later lives. However, whether GWG is a strong predictor of body mass index (BMI) 2 decades after the index pregnancy is unknown. OBJECTIVE We examined the long-term effect of GWG by using a community-based birth cohort study. DESIGN We followed a subsample of 2055 women from an original cohort of 7223 women who gave birth in Brisbane, Australia, between 1981 and 1983. Multivariable regression and multinomial regression were used to examine the independent associations of GWG per gestational week and Institute of Medicine (IOM) categories of combined prepregnancy BMI and GWG with BMI and its categories 21 y after the index pregnancy. RESULTS In analyses using GWG per week as a continuous exposure variable, maternal BMI (in kg/m(2)) increased, on average, by 0.52 (95% CI: 0.31, 0.73) for a 0.1-kg/wk greater GWG. This association became stronger when adjusted for maternal prepregnancy BMI. Analyses with IOM categories showed a greater postnatal increase in BMI for women defined as having excessive GWG (3.72, on average; 95% CI: 3.12, 4.31) than for women with adequate GWG. The women who gained excess weight during pregnancy had increased odds of being overweight [odds ratio (OR): 2.15; 95% CI: 1.64, 2.82] or obese (OR: 4.49; 95% CI; 3.42, 5.89) 21 y after the index pregnancy. These associations were independent of other potential factors. CONCLUSION Weight gain during pregnancy independently predicts the long-term weight gain and obesity of women.

Maternal cigarette smoking and child psychiatric morbidity: a longitudinal study.

Objective. Previous studies have linked maternal smoking during pregnancy with behavioral disturbance in children. However, additional evidence is needed to address the causality of the relationship. The present study analyses result from an Australian cohort of 5342 5-year-old children whose mothers were recruited early in pregnancy. Methods. Smoking history was gathered for prepregnancy, first clinic visit (FCV), late pregnancy, and when the child was 6 months and 5 years of age. Behavior problems at the age of 5 were assessed using a modified Child Behavior Check List (CBCL) shown to have high agreement with the complete CBCL. This resulted in the formation of three scales: internalizing; social, attentional and thought; and externalizing behavior problems, which were then dichotimized at the 90th percentile in each case. Logistic regression was used to model these outcomes as a function of maternal smoking at five time points during which it was assessed. A series of models explored the effect of additional adjustment for confounding. The predictors of attrition (29.5%) throughout the cohort were also identified by multivariate modeling. Results. The final analysis was carried out on a cohort of mother-child pairs for whom data and child behavior outcomes were complete. The mean age of children was 5 years, 6 months with a range from 4 to 6 years. The mean age of mothers at the time of birth of the child was 25 years, with a range from 13 to 47 years. Mothers lost to follow-up were more likely to be younger, single, and less well-educated than those who continued participation, although maternal smoking was not an independent determinant. Unadjusted analyses showed strong associations between externalizing child behavior and maternal smoking during pregnancy and at the 5-year follow-up, with relative risks (RRs) up to 2.6 for children of women smoking at least 20 cigarettes per day at the first antenatal clinic visit. A clear dose-response relationship existed in most relationships with higher levels of smoking being associated with higher rates of externalizing behavior problems. Weaker relationships occurred for internalizing behavior and social, attentional and thought behavior problems. Multivariate analysis of the timing in more detail that the association between maternal smoking and child behavior problems persisted, although the evidence for dose-response diminished. Moreover, it was primarily associated with smoking as determined by questions asked at the FCV (RR = 1.52, 2.03, 2.16) for 1 to 9, 10 to 19, and ≥20 cigarettes per day, respectively, compared with nonsmoking and secondarily by smoking determined at the 5-year follow-up (RR = 1.52, 1.87, 1.29) for 1 to 9, 10 to 19, and ≥20 cigarettes per day respectively, compared with nonsmoking. This association appeared to be independent of a wide range of possible confounders such as maternal age, education, social class, marital status and mental health, gestation at FCV, complications during pregnancy, the childs sex, gestational age at birth, and age at last follow-up. Adjustments were also made for the mothers employment since birth, family structure, and maternal mental health at the time of the CBCL assessment. Associations between externalizing behavior problems and maternal smoking at other times, and those between other behavioral problems examined and maternal smoking were not significant. Conclusion. Although previous studies have found evidence for an association between maternal smoking and child behavior problems, the strength of this study lies in its size, its detailed and consistent measurement of maternal smoking, and its ability to control for many social and biological factors linked to maternal smoking and child behavior. The statistical evidence for a causal relationship between maternal smoking as measured at the first antenatal clinic visit and the development of externalizing behavior in children is strongly suggestive, because of the specificity of effect and timing, and the adjustment for a comprehensive range of other risk factors. An alternative explanation that mothers who smoke might be inclined to report behavior problems differently was considered unlikely because the effect was specific to externalizing behavior and the major exposure occurred 5 years before the reported behavior. Additionally, the existence of a factor (beyond those already included in the analysis) that might be related to both behavior problems and any propensity to misreport smoking seems sufficiently implausible to rule out misclassification of smoking status as another alternative explanation for the findings. The timing of the relationship between smoking in pregnancy and externalizing behavior problems, and its independence of small for gestational age status at birth, suggests that placental insufficiency and oxygen deprivation are not important in the pathogenesis. It is possible that nicotine in the fetal brain derived from maternal smoking may alter gene expression and the nature and function of the nicotine receptors developing in early pregnancy. The presence of a separate, although slightly weaker, association between concurrent maternal smoking and externalizing child behavior suggests both biological and social explanations, including a direct psychopharmocologic effect of nicotine through passive smoking. Assuming the relationship to be causal, it is estimated that maternal smoking in early pregnancy may account for 25% of externalizing (aggressive) behavior while maternal smoking when the child is 5 years old may account for an additional 16%. These findings provide further support for antismoking programs in pregnancy and in young family settings.

Association between cannabis use and psychosis-related outcomes using sibling pair analysis in a cohort of young adults.

CONTEXT Prospective cohort studies have identified an association between cannabis use and later psychosis-related outcomes, but concerns remain about unmeasured confounding variables. The use of sibling pair analysis reduces the influence of unmeasured residual confounding. OBJECTIVE To explore the association between cannabis use and psychosis-related outcomes. DESIGN A sibling pair analysis nested within a prospective birth cohort. SETTING Births at a Brisbane, Australia, hospital. PARTICIPANTS Three thousand eight hundred one young adults born between 1981 and 1984 as part of the Mater-University Study of Pregnancy. MAIN OUTCOME MEASURES Cannabis use and 3 psychosis-related outcomes (nonaffective psychosis, hallucinations, and Peters et al Delusions Inventory score) were assessed at the 21-year follow-up. Associations between duration since first cannabis use and psychosis-related outcomes were examined using logistic regression adjusted for sex, age, parental mental illness, and hallucinations at the 14-year follow-up. Within 228 sibling pairs, the association between within-pair differences in duration since first cannabis use and Peters et al Delusions Inventory score was examined with general linear modeling. The potential impact of attrition was examined. RESULTS Duration since first cannabis use was associated with all 3 psychosis-related outcomes. For those with duration since first cannabis use of 6 or more years, there was a significantly increased risk of (1) nonaffective psychosis (adjusted odds ratio, 2.2; 95% confidence interval, 1.1-4.5), (2) being in the highest quartile of Peters et al Delusions Inventory score (adjusted odds ratio, 4.2; 95% confidence interval, 4.2-5.8), and (3) hallucinations (adjusted odds ratio, 2.8; 95% confidence interval, 1.9-4.1). Within sibling pairs, duration since first cannabis use and higher scores on the Peters et al Delusions Inventory remained significantly associated. CONCLUSIONS Early cannabis use is associated with psychosis-related outcomes in young adults. The use of sibling pairs reduces the likelihood that unmeasured confounding explains these findings. This study provides further support for the hypothesis that early cannabis use is a risk-modifying factor for psychosis-related outcomes in young adults.

Bias influencing maternal reports of child behaviour and emotional state

Background: Previous research has indicated that there may be only a modest degree of agreement between different reporters of a childs behaviour (mental health). This raises the possibility that some descriptions of the childs behaviour may reflect the personal characteristics of the respondent. We examine two potential sources of bias that may influence reports of a childs behaviour/mental health. The first is the mental or emotional impairment of the respondent; the second concerns gender-related expectations of children. Methods: Mothers (and their children after the birth) were assessed at first clinic visit, 3–5 days after the birth, then 6 months, 5 years and 14 years after the birth. Some 70% of respondents giving birth remained in the study at the 14-year follow-up, leaving some 5277 cases for this analysis. At the 14-year follow-up, child behaviour (mental health) was assessed using the Child Behaviour Check List and the Youth Self Report. Maternal mental health was determined using the anxiety and depression subscales of the Delusions-Symptoms-States Inventory. Results: Mothers who were not emotionally impaired reported fewer child behaviour problems than did the children themselves. As the mothers current emotional impairment increased, so her reports of the childs behaviour problems increased, when compared with the childs own reports. Further, mothers attributed more internalising symptoms to female respondents, and more externalising symptoms to male respondents, than did the child respondents themselves. Conclusions: Mothers differ systematically from their children when they are reporting their childs behaviour (mental health). The more emotionally impaired the mother, the greater the degree to which she imputes the child to have behaviour problems. Further, female children are attributed to have more internalising behaviours and male children externalising behaviours.

Cannabis use and educational achievement: Findings from three Australasian cohort studies

BACKGROUND The associations between age of onset of cannabis use and educational achievement were examined using data from three Australasian cohort studies involving over 6000 participants. The research aims were to compare findings across studies and obtain pooled estimates of association using meta-analytic methods. METHODS Data on age of onset of cannabis use (<15, 15-17, never before age 18) and three educational outcomes (high school completion, university enrolment, degree attainment) were common to all studies. Each study also assessed a broad range of confounding factors. RESULTS There were significant (p<.001) associations between age of onset of cannabis use and all outcomes such that rates of attainment were highest for those who had not used cannabis by age 18 and lowest for those who first used cannabis before age 15. These findings were evident for each study and for the pooled data, and persisted after control for confounding. There was no consistent trend for cannabis use to have greater effect on the academic achievement of males but there was a significant gender by age of onset interaction for university enrolment. This interaction suggested that cannabis use by males had a greater detrimental effect on university participation than for females. Pooled estimates suggested that early use of cannabis may contribute up to 17% of the rate of failure to obtain the educational milestones of high school completion, university enrolment and degree attainment. CONCLUSIONS Findings suggest the presence of a robust association between age of onset of cannabis use and subsequent educational achievement.

Maternal anxiety and depression, poverty and marital relationship factors during early childhood as predictors of anxiety and depressive symptoms in adolescence

BACKGROUND This paper examines the degree to which symptoms of anxiety and depression at age 14 years are associated with early childhood experience of maternal anxiety and depression, poverty, and mothers marital relationship distress and break-up. METHODS In a longitudinal study, 4434 families were followed-up from infancy to adolescence. RESULTS Maternal anxiety and depression during early childhood were found to have small, but significant, influences upon the development of high anxiety-depression symptoms at age 14, after controlling for the effects of poverty and marital relationship factors. This effect was greater with repeated exposure to high maternal anxiety and depression. Poverty, distressed marital relationship and marital break-up during the childs first five years also produced small, but significant, increases in risk of high anxiety and depression symptoms in adolescence. Stable, single-parent status was not found to be a risk factor. There was no evidence of marked gender differences in risk factors, other than poverty, which had a stronger impact for girls than boys. CONCLUSIONS Overall, the results suggest that maternal anxiety and depression, poverty, parent relationship conflict and marital break-up during early childhood are associated with small, but significant, increased risk of anxiety-depression symptoms in adolescence.